The halls of Sterling Cooper & Partners have been filled with a lot of familiar faces lately. Here are more than 20 "Mad Men" guest stars we recognize from previous roles in TV and movies. — Dave Nemetz, Yahoo! TV

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Alexis Bledel

In Season 5, Pete Campbell (Vincent Kartheiser) strayed outside his marriage with troubled housewife Beth Dawes, played by none other than "Gilmore Girls" alum Alexis Bledel. The affair didn't end well — Beth ended up in the loony bin, actually — but the pairing certainly clicked in real life: Kartheiser and Bledel are now married.